1 introduction - european coatings journal€¦ · 18 basf handbook on basics of coating technology...

BASF Handbook on Basics of Coating Technology 15

Fig. 1.1.1Coated objects of daily life

Definition, tasks and economic importance

1 Introduction

1.1 Definition, Tasks and Economic ImportanceThe task of coating technology is to provide surface protection, decorative finishes andnumerous special functions for commodities and merchandise by means of organic coat-ings. Many everyday products are only made usable and thus saleable because of theirsurface treatment. To achieve this, relevant coating formulations, their production plant,the coating material and suitable coating processes for the product must be available.However, the quality to be achieved by means of the coating process is not the onlyfunction of the coating material used. The object to be painted or coated itself with itsspecific material and design and anappropriate application process arefurther variables which play a sig-nificant role. In addressing the on-going tasks of quality optimizationand rationalisation while minimiz-ing the impacts for humans and theenvironment, it is vital that the de-pendencies mentioned above be notonly recognized but also taken intoaccount as the framework definingthe conditions in which work is car-ried out from development to appli-cation. Coating technology, there-fore, is an interdisciplinary subject.Paints and coating materials are notend products, but merely initial orintermediate products which, for theabove mentioned reasons, require a skilled and conscientious user if they are to be con-verted into the actual end product, the coating itself. Only the cured coating, in manycases a system consisting of several individual coats, may meet the wishes invested inand the requirements demanded of the coated products.Two of the most important of the many functions which coatings have to meet are pro-tection and decoration. Other noteworthy features are the informative tasks and theachievement of special physical effects. The conspicuousness of emergency servicevehicles, the camouflaging of military equipment, and road or airport markings are justsome of the informative tasks required of coatings. Color markings enable areas orspaces to be clearly signed or divided. Color coding helps to indicate the contents ofcontainers or the material being conveyed in pipes. Optical effects induced by coloredor metallic pigments lend a coating a particular optical attraction. Deliberately gener-ated surface textures such as scars or wrinkles expand the range of effects which can beachieved. The use of color schemes for rooms and machines based on known physi-

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BASF Handbook on Basics of Coating Technology16

Introduction

ological and psychological effects of colors also contributes in various ways toimproved working conditions and enhanced safety. Functional pigments produce tem-perature dependent colors, for example as a result of their thermochromic properties,and therefore, indirectly permit the temperatures of objects to be measured.The most important task for coatings, in economic terms, is surface protection. Thuscoatings help to retain value and improve the usability properties of almost all productsand are therefore, of huge economic significance. Particular mention should be made ofthe protection of goods made of metals which only gain lasting anticorrosive protectionwhen they are painted.

It is vital in this regard, for ex-ample, in the automotive sec-tor, for the resistance of thecoating system to external,sometimes aggressive naturaland anthropogenic atmosphericinfluences such as tree resins,bird droppings, acids, alkalis,salts and organic solvents, to beguaranteed.The protective function ofpaint on cars must not be im-paired even under extreme me-chanical impacts such as stonechippings thrown up from theroad by traffic or by brush ac-tion in carwashes.Furthermore, coatings must

withstand combined, i.e. physical and chemical, effects to which objects are subjected,for example, in the different weather conditions. The interaction of sunshine, rain, heatand frost combined with emissions from heating systems and internal combustion en-gines, by ozone and saline fog makes great demands on a coating’s resistance and pro-tective properties.However, a surface protection coating can also be applied in order to meet quite differ-ent requirements. Floors and steps can be made nonslip by means of rough or high gripcoatings, thereby increasing their utility value. By contrast, surface friction can be re-duced by use of smooth coatings to produce a high degree of nonadhesiveness. Flam-mable materials can be rendered safe by means of flame retardant coatings. Antibacte-rial coatings help maintain sterile surfaces in production and storage facilities in dairiesand breweries or prevent the growth of barnacles and algae on ships’ hulls. In the elec-trical engineering sector insulating coatings provide effective and lasting insulation forwire, windings and condenser materials. On the other hand, conductive coatings can beused to make insulating substrates electrically conductive or even to print electricalcircuits. Furthermore, organic coatings can help to reduce noise pollution. Acousticalinsulation coatings for machines and underbody protection coatings for passenger carsare examples of this.

Fig. 1.1.2Factors determining the quality of coatings

Process Substrate

Coating Design

EcologicalRequirements

EconomicalRequirements

Final Quality

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This broad spectrum of require-ments explains why no single coat-ing material can satisfy every wishsimultaneously and in the sameway. The goal of providing coat-ing materials for the durable pro-tection, decoration and impro-vement of objects made of wood,metal, plastic or mineral materialsat reasonable prices can only bemet by adopting different formu-lations using a range of materialsand material combinations. Eachof these combinations targets alimited field of substrates, a se-lected application method and aspecific profile of film properties.Coating technology is used in metal processing, in the manufacture of plant and ma-chinery and in the electrical engineering industry. All kinds of road and rail vehicles,ships and aircraft are important objects which require painting or coating. Effectivesurface protection by means of paints and coatings is also indispensable in the civilengineering sector, for steel and concrete structures and in wood processing. Even plas-tics and leather require coating in many cases. Modern paper, plastic or sheet metalpackaging materials are inconceivable without the protection and decoration affordedby coatings.The worldwide paint and coatings market reflects economic developments in the re-gions. It is most highly developed, for example, in the so called triade (North America,Europe, South East Asia). The per capita consumption of paints and coatings in theseregions is approx. 4.5 kg. The growth in coating consumption is determined by theeconomic development in the individual regions or countries [1.3.1].The broad field of applications for coatings and their widespread use are explained bythe high value and great benefits which they offer. The fact that there are few objectswhich do not require coating is an indication of the enormous importance of coatingtechnology. Calculating this importance merely in terms of the quantity of coating ma-terials manufactured annually worldwide of 28.6 million tonnes in 2006 with a value ofsome 80 billion euros (fig. 1.1.3) gives an incomplete picture.Although quoting the quantities of coating materials is not a direct indication of theadded value of industrial commodities, it does permit the area which can be protected ordecorated by means of coating materials to be calculated, taking due account of the filmthickness to be applied. Assuming an annual production quantity of 28.6 million tonnesand a wet film thickness of 100 µm (0.1 mm), a surface area of some 315,000 km2 canbe coated. That represents about 3/4 of the surface area of Germany. A 10 m wide stripwith a film thickness of 100 µm, on the other hand, coated using the same quantity ofpaint would stretch about 100 times from the earth to the moon or go round the world600 times.

Fig. 1.1.3World coatings market of 28.6 mio tons in 2006 by regions

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Introduction

A more meaningful means of evaluation would be to use the value of the effectivelyprotected and improved products. Assuming that an added value of 20% of the pro-duced goods is achieved by painting or coating them in the form of an extended servicelife and increased attractiveness, this means EUR 200 billion for the German market in2000. This represents 50 times the sales value of the paints and coatings.

The division of the mar-ket into branches or seg-ments is not uniformaround the world. Anumber of breakdowns,however, seem agreed onusing certain segments,such as decorative paints,general industrial paints,automotive paints, andprinting inks.Decorative paints repre-sent the largest market for

paints and coatings at 53%. This is followed, at 29%, by the market for the industrialcoating of a huge range of objects, from compact discs via plastic bumpers for cars torail vehicles (see chapter 7). Automotive coating lines and refinishing bodyshops areeach clearly defined segments with a high technological value, though of less signifi-cance in terms of volume sales. Printing inks represent approx. 4% of the worldwidedemand for coating materials and are a separate segment in technological and market-ing terms, though not from the point of view of their composition.The size of the European market was 9.1 million tonnes in 2006. There is a slight shifttowards industrial coatings and printing inks compared with the sectoral division in therest of the world. Germany is the leader with a consumption of approx. 1.6 milliontonnes ahead of Italy, France, the UK and Spain, which are all in the range between 0.7and 0.8 million tonnes. The size of the Northamerican market was 21.2 Bio. US $ in2002 served by about 835 companies [1.3.2]The graphic below gives an overview of the economic development of the paint andcoatings industry in Germany since 2000 which is closely linked to the country’s over-all economic development.One of the characteristic features of coating technology in addition to coating consump-tion is the still high energy consumption for processing coatings which is estimated atapprox. 200 billion kWh annually worldwide. This figure is the equivalent of the energycontent of approx. 30 million tonnes of crude oil. If the raw materials required for paintproduction are also added to this figure in the form of crude oil equivalents, the result isa total crude oil requirement of approx. 100 million tonnes for the worldwide manufac-ture and processing of coating materials, or some 3 to 4% of the annual crude oil extrac-tion worldwide.The legal requirements imposed on environment compatible coating processes haveresulted in greater use of appropriate coating materials in the last 20 years. Theseinclude, in particular, solvent free powder coatings, waterborne paints, in which organic

Fig. 1.1.4Worldwide coatings market in 2006 by segments (source : VdL)

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solvents are replaced inwhole or in part by water,high solids paints and radia-tion curable paints, which areprocessed either in an aque-ous solution or completelywithout conventional sol-vents with the aid of low mo-lecular reactive thinners (seechapter 5). Statistics from theAssociation of the GermanPaint Industry (VdL) showthat these coatings haveachieved the greatest growth,with a 10% annual increasein the last 10 years.Ongoing improvements inour knowledge of the toxicol-ogy of the raw materialsentail a regular replacement of raw materials, which is associated with the correspond-ing development costs, if we wish to maintain the quality standard achieved.As far as energy consumption is concerned, there is still a need to be more economicalin the use of raw materials and energy. A proportion of the material is lost en route to thefinished coating. Spray application, which is specified for many objects to be paintedbecause of its optical attractiveness and range of colours, has a particular role in thisregard. As far as coating wood and plastics is concerned, the more effective electrostaticspray methods have not yet found universal acceptance. In addition, the paintlines losesubstantial quantities of heat energy. In recent years a number of developments haveincreased the efficiency of coating processes to such an extent that growth in the paintand coatings market in the industrially developed countries has been below the growthlevel of the gross domestic product (GDP).As a result of the use of solvents as an application aid for coatings, an additional hydro-carbon emission load of approx. 200,000 tonnes is estimated annually in 2007 for Ger-many alone for the currently standard average organic solvent content of 50% [1.3.3].Whereas the organic emissions from motor vehicles have been successfully reduced toless than 1/3 of their previous level in the last 20 years by the introduction of the cata-lytic converter, the successes in coating technology have been more modest to date bycomparison. Despite the introduction of waterborne paints and powder coatings, ap-proximately half of all the industrially processed coating materials used in Germany arestill in the form of conventional, i.e. solventbased materials.From a European perspective, the solvent processing industries, including the paint andcoatings industry, are now the leading emitters of organic compounds and solvents.European legislators responded to this fact by issuing a 1999 EU directive (see chapter5.3) in an attempt to force even small to medium sized companies to adopt more strin-gent measures to avoid emissions.

Fig. 1.1.5Production of coatings in Germany from 2000 to 2006

In more than 200 manufacturing plants with a total of 20,000people about 2.3 million metric tons of coatings have beenproduced representing a value of 4.8 billion Euros in the year2006.

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Introduction

Significant success has beenachieved by manufacturers andprocessors of paints and coat-ings with regard to occupationalhealth and safety. The chemicalindustry, for example, has ledthe accident statistics in Ger-many for the industry with theleast number of incidents.An analysis of this situation re-veals that manufacturers andconsumers of paints and coat-ings, though occupying differentvalue added stages, are extrem-

ely closely connected. Manufacturers develop and supply coatings materials to the con-sumers who in turn modify the product while processing them in physical, physico-chemical and chemical processes and convert them in this way into a bound, mechani-cally solid and, at the same time, flexible coating.The path of chemistry from the raw material to the finished coating starts at the rawmaterials or paint manufacturer and is then consciously interrupted before it is taken upagain during processing by the paint consumer.Although the performance profile of a coating is initially shaped by the paint and thusby the paint manufacturer, it is the processor who actually generates the finished prop-erties. The industrial scale coating of consumer goods is therefore a joint effort betweenpaint and coatings manufacturers and processors.

Fig. 1.1.6German coatings market in 2006 by product classes(source : VdL)

ProcessSequence

LineSpeed

ApplicationEquipment

ApplicationParameters

Flash OffTime /

Air Conditions

Layer DistributionRatio

Filmbuilt1 or 2 Coat

Appearance

Substrate Flash Off /Curing

PaintMaterial

ReciprocationMovement

VoltageFlow Rates

ObjectTemperature

Distanceto Target

R.P.M.Bell

ClimateConditions

VolumeAtomizing Air

VolumeShaping Air

AirlessAirmix

ESTATribo

PneumaticHVLP

High RotationMicro-/Ecobel

SurfaceRoughness

SurfaceStructure

SurfaceTension

Material

Conductivity

Pretreatment

Time

OvenCurve

Temperature

HeatingDirect / Indirect

Temperature

Rheology

SolidContent

EvaporationKinetics

Viscosity

SurfaceTension

Fig. 1.1.7Various factors determining the final coating result of the spray application process

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1 introduction - european coatings journal€¦ · 18 basf handbook on basics of coating technology...

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